A chorus of Democratic senators is raising objections to a bill designed to help small businesses – throwing bumps in the road to passage of the legislation that had sailed through the GOP-led House and won President Barack Obama’s endorsement.

The Democratic lawmakers warned that the House bill would loosen financial oversight so much that it would weaken safeguards for consumers and investors, even potentially triggering another economic crisis or Enron-style scandal.

“The idea that it could succeed without the opportunity to put back protections for consumers to me is incredible,” Sen. Carl Levin (D-Mich.) said Thursday. “I am frankly stunned by the speed with which these special interest folks representing very powerful interests in this country have been able to move this bill through the House, and we’re going to try to see if we can’t build in some protections in the Senate.”

Senate Majority Leader Harry Reid (D-Nev.) scheduled votes for Tuesday on a substitute version of the House-passed JOBS Act – for Jumpstart Our Business Startups – as well as a measure that would renew the mandate of a federal exports agency that Democrats say will create thousands of jobs.

The substitute version pushed by Levin and fellow Democratic Sens. Jack Reed of Rhode Island and Mary Landrieu of Louisiana will better protect consumers and investors, the senators argue – but it’s almost certain that it’ll fail to get the 60 votes needed to pass.

“It’s going to be tough,” Sen. Mark Begich (D-Alaska) said of the 60-vote threshold.

GOP senators prefer to take up the House bill, which passed last week by a 390-23 vote. The House version is a package of six bills meant to ease various Securities and Exchange Commission regulations that would help small businesses raise more capital.

“Here’s a chance not only to help entrepreneurs build their businesses and create jobs, but to show that we can work together around here to get things done on a bipartisan basis,” Senate Minority Leader Mitch McConnell (R-Ky.) said Thursday.

But Democratic senators said they have issues with the House package and want to slow things down.

“We ignore history if we turn our backs on 80 years of this government stepping up to make sure that the marketplace in America was safe for investors, to make sure that the person selling you a stock was actually a well-qualified person,” Senate Majority Whip Dick Durbin (D-Ill.) said Wednesday.

Sen. Jeff Merkley (D-Ore.), who’s also voiced objections to a provision in the House bill that would allow small businesses to raise smaller amounts of funding from investors, said he would “absolutely not” back the legislation without changes.

Proponents of the House version said there were already sufficient protections for investors written into the JOBS Act.

“Senate Democrats are working overtime to find excuses to delay and water down the bipartisan JOBS bill,” a senior Republican aide said. “Rather than claiming the sky is falling, if Senate Democrats want to help America’s job creators, they should work quickly to advance the House-passed JOBS bill that is supported by the president and the business community.”

Meanwhile, Democrats are hoping to lure enough Republican senators to back reauthorization of the Export-Import Bank, a federal agency that helps finance U.S. exports through loans and other forms of insurance. Republicans senators such as Lindsey Graham of South Carolina and Richard Shelby of Alabama are co-sponsoring that measure, which Democrats hope will bolster chances of its passage.

The Export-Import Bank’s mandate is set to expire in May, and the measure would not only reauthorize it until 2015 but also raise the agency’s lending cap from $100 billion to $140 billion.

“I think it’s a very good sign to have the ranking Republican on the Banking Committee sponsoring [the] amendment,” Reid told POLITICO, referring to Shelby.

The U.S. Chamber of Commerce backs reauthorization of the Export-Import Bank, but conservative organizations such as the Club for Growth and Heritage Action have urged senators to reject the measure.